Can't help up on UK info sorry. But we're in a similar situation in Australia with all imports being a total rippoff. I've just ordered an Iwata airbrush from Dixieart in the US so will have to wait and see how their service pans out.
Decided to upgrade from my single action, external mix Paashe that I've had for a long time. A good dependable brush but not capable of the finer work I hope the Iwata can do. I did a bit of reaserch, including talking to guys like Dan on this forum, and decided Iwata seemed the best. Can't wait to get my hands on it but will be a few weeks yet.